ISOLATION AND CHARACTERIZATION OF 3 POSITIONAL ISOMERS OF DIGLUCOSYLCYCLOMALTOHEPTAOSE

Three positional isomers of diglucosylcyclomaltoheptaose [(G)2-β-cyclodextrin], 61,64-di-O-(a-d-glucopyranosyl)-cyclomaltoheptaose (1), 61,63-di-O-(a-d-glucopyranosyl)-cyclomaltoheptaose (2), and 61,62-di-O-(a-d-glucopyranosyl)-cyclomaltoheptaose (3) were isolated by h.p.l.c. on a reversed-phase column from the mother liquors of a large-scale preparation of βCD with Bacillus ohbensis cyclomaltodextrin glucanotransferase (EC 2.4.1.19) and were characterized by h.p.l.c. analysis of partial hydrolyzates and by 13C-n.m.r. spectroscopy. Their molecular weights were confirmed by f.a.b.-m.s. Their characteristic chromatographic behavior on four h.p.l.c. columns of different separation modes was found to be very useful for their identification. It is particularly noteworthy that the first application of a graphitized carbon column to CDs enabled a fine separation of all three positional isomers. © 1990.